JPH0228630B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a novel liquid crystal compound and a liquid crystal composition containing the liquid crystal compound and suitable for use in liquid crystal display elements, liquid crystal light shutters, and the like. [Prior Art] Compounds containing optically active groups are attracting attention as liquid crystal compounds. The functions of compounds characterized by containing optically active groups include those that utilize the White-Taylor guest-host type electro-optical effect that utilizes a chiral nematic phase in the liquid crystal state, and those that utilize a chiral nematic phase to a nematic phase. Some of the known methods are those that utilize the phase transition phenomenon caused by an electric field, those that utilize the phase transition phenomenon that occurs due to heat between the chiral nematic phase and the smectic phase, and those that utilize the ferroelectric phenomenon of the smectic phase. Further, by forming a monomolecular cumulative film, it can be used as a nonlinear optical element, and by immobilizing it in a matrix, it can be used as an optical element such as a circularly polarized beam splitter or a filter. Therefore, research has been carried out to synthesize compounds containing optically active groups, examine their functions, and apply them to the various uses mentioned above. Further, conventionally known liquid crystal display elements include TN (Twisted Nematic) type, dynamic scattering type (DS type), guest-host type, and those using thermo-optic effects. In particular, TN type liquid crystal elements are widely used in watches, calculators, etc., but because of their slow response, they are not fully satisfactory for liquid crystals that require high-speed response, such as optical shutters, television image display devices, computer terminal display devices, etc. is the current situation. To improve the drawbacks of conventional liquid crystal devices, Clark and Lagerwall proposed the use of bistable liquid crystal devices (Japanese Patent Application Laid-open No. 107216/1983, U.S. Patent No.
4367924 specification, etc.). Bistable liquid crystals are generally chiral smectic C phase (SmC*).
H phase (SmH*), F phase (SmF*), I phase (SmI
*), a ferroelectric liquid crystal having a chiral smectic phase such as G phase (SmG*) is used. This liquid crystal has a bistable state consisting of a first optically stable state and a second optically stable state with respect to an electric field. For example, the liquid crystal is oriented in the first optically stable state with respect to one electric field vector. For other electric field vectors, the liquid crystal is oriented in a second optically stable state. Furthermore, this type of liquid crystal has the property of very quickly taking one of the above two stable states in response to an applied electric field, and maintaining that state when no electric field is applied. Next, the operation of the ferroelectric liquid crystal will be explained using FIGS. 1 and 2. 1 and 1a in Figure 1
is In ₂ O ₃ , SnO ₂ or ITO (Indium-
A substrate (glass plate) coated with a transparent electrode made of a thin film such as TinOxide, etc., between which a liquid crystal molecular layer 2 is oriented perpendicular to the glass surface.
*phase or SmH* phase liquid crystal is enclosed. A thick line 3 represents a liquid crystal molecule, and this liquid crystal molecule 3 has a dipole moment (P⊥) 4 in a direction perpendicular to the molecule. Boards 1 and 1a
When a voltage higher than a certain threshold is applied between the upper electrodes, the helical structure of the liquid crystal molecules 3 is unraveled, and the liquid crystal molecules 3 are able to change their alignment direction so that all of the dipole moments (P⊥) 4 point in the direction of the electric field. can. The liquid crystal molecules 3 have an elongated shape and exhibit refractive index anisotropy in the long axis direction and the short axis direction. Therefore, for example, if crossed Nicol polarizers are placed above and below the glass surface, voltage can be applied. It is easily understood that this results in a liquid crystal optical modulation element whose optical properties change depending on the polarity. The liquid crystal cell preferably used in this field has a sufficiently thin thickness (for example, 10μ or less).
can do. As the liquid crystal layer becomes thinner, the helical structure of the liquid crystal molecules unravels even when no electric field is applied, as shown in Figure 2.
It has a non-helical structure, and its dipole moment P or Pa takes either an upward direction 5 or a downward direction 5a. In such a cell, an electric field E or Qa of different polarity above a certain threshold value is applied as shown in Figure 2.
is applied by the voltage application means 6 and 6a, the dipole moment changes its direction upward 5 or downward 5a in response to the electric field E or the electric field vector of Ea, and accordingly, the liquid crystal molecules enter the first stable state 7.
or the second stable state 7a. As mentioned earlier, there are two advantages to using such ferroelectricity as an optical modulation element. The first is that the response speed is extremely fast, and the second is that the response speed is extremely fast.
is that the orientation of liquid crystal molecules has bistability. To further explain the second point, for example, with reference to FIG. 2, when an electric field E is applied, the liquid crystal molecules are oriented in a first stable state 7, and this state remains stable even when the electric field is turned off. Furthermore, when an electric field Ea in the opposite direction is applied, the liquid crystal molecules are oriented to the second stable state 7a and change their orientation, but they remain in this state even after the electric field is turned off. Further, as long as the applied electric field E does not exceed a certain threshold value, each orientation state is maintained. In order to effectively realize such fast response speed and bistability, it is preferable that the cell be as thin as possible. Specific examples of the above-mentioned liquid crystal compounds exhibiting ferroelectricity include p-decyloxybenzylidene-p'-amino-2-methylbutylcinnamate (DOBAMBC), p-hexyloxybenzylidene-p'-amino-2-chloropropyl Examples include cinnamate (HOBACPC), 4-D-(2-methyl)-butylresolcylidene-4'-octylaniline (MBRA8), and the like. However, when this compound is repeatedly energized as a liquid crystal element, it tends to deteriorate, and care must be taken in terms of the airtight sealing conditions of the cell, operating conditions, etc., and this is a major difficulty in the development of liquid crystal elements. On the other hand, although searches have been made for stable liquid crystal compounds, no one that satisfies high-speed response and stability and has been put to practical use has yet to be found. [Problems to be Solved by the Invention] The present invention provides a novel liquid crystal compound containing an optically active group that is effective for the various uses listed above, and a method for incorporating the new compound into a ferroelectric liquid crystal. This invention was developed in order to provide a liquid crystal composition that has excellent operating life characteristics, fast response speed, and excellent bistability, and is suitable for use in liquid crystal display elements, liquid crystal shutters, etc. . [Means and effects for solving the problems] According to the present invention, (1) General formula (): (In the formula, R represents an alkyl group having 6 to 12 carbon atoms,
* indicates an asymmetric carbon atom) A ferroelectric liquid crystal composition is provided, which is characterized by containing at least one compound represented by the following as a compounding component. If the chain length of the alkyl group R in the general formula () is too short, it will lack stability when mixed into a ferroelectric liquid crystal, resulting in a high phase transition temperature, while if the chain length is too long, There are disadvantages of increased melting point and increased viscosity, and from the balance thereof, the number of carbon atoms in the alkyl group R is preferably 4 to 20, more preferably 6 to 16, particularly preferably 6 to 12. . Preferred specific examples of 4-(β-methylbutyloxy)-4'-alkylazoxybenzene represented by the above general formula () include S-(+)-4-
(β-methylbutyloxy)-4′-hexylazoxybenzene, S-(+)-4-(β-methylbutyloxy)-4′-heptylazoxybenzene,
S-(+)-4-(β-methylbutyloxy)-
4'-octylazoxybenzene, S-(+)-4
-(β-methylbutyloxy)-4'-nonylaxyzobenzene, S-(+)-4-(β-methylbutyloxy)-4'-decylazoxybenzene, S
-(+)-4-(β-methylbutyloxy)-
4'-Undecylazoxybenzene, S-(+)-
4-(β-methylbutyloxy)-4'-dodecylazoxybenzene is mentioned. Next, a method for producing the novel liquid crystal compound of the present invention will be described. First, p-alkylaniline is added dropwise to an aqueous solution of hydrochloric acid under cooling to form a hydrochloride. Next, a sodium nitrite aqueous solution is added dropwise to form a diazonium salt. This diazonium salt aqueous solution is added dropwise to phenol under alkaline conditions to synthesize 4'-alkyl-4-hydroxyazobenzene. After purifying 4'-alkyl-4-hydroxyazobenzene, it is reacted with excess potassium hydroxide and then with optically active 2'-methylbutyl bromide to obtain 4-(β-methylbutyloxy)4'-alkylazobenzene. . 4-(β
-Methylbutyloxy)-4'-alkylbenzene is purified, dissolved in glacial acetic acid, heated to 60-70℃, added hydrogen peroxide solution and reacted, separated and purified to produce 4-
(β-methylbutyloxy)4′-alkylazoxybenzene is obtained. The chemical formula for the above is as follows. 4-(β-methylbutyloxy)- of the present invention
4'-Alkylazoxybenzene is an optically active substance and mainly exhibits a cholesteric phase. A small amount of the compound of the present invention can be added to a nematic liquid crystal to obtain a liquid crystal composition for use in a White-Taylor type display element or a phase transition type display element from a chiral nematic phase to a nematic phase.
It can be added to liquid crystal compositions used in TN display elements to prevent the occurrence of reverse domains. Further, as the liquid crystal compound used in the liquid crystal composition containing the compound represented by the general formula () of the present invention and having ferroelectric properties, Smectic C
A liquid crystal compound having a phase, preferably SmC* or a ferroelectric liquid crystal compound having a chiral smectoid phase is used. Next, the liquid crystal composition of the present invention will be explained. Specific examples of ferroelectric liquid crystal compounds used in the liquid crystal composition of the present invention are listed below. Schiff base type ferroelectric liquid crystal compound: (1) DOBAMBC (p-decyloxybenzylidene p'-amino-2-methylbutylcinnamate) (Compounds in this family having an alkoxy group with the number of carbon atoms ranging from p-hexyloxy to p-decyloxy have ferroelectric properties and can be used in the composition of the present invention.) (2) DOBAMBCC (p-decyloxybenzylidene p '-Amino-2-methylbutyl α-cyanocinnamate) (Compounds in this series in which p-decyloxy group is replaced with p-tetradecyloxy group are also ferroelectric.) (3) OOBAMBCC (p-octyloxybenzylidene p'-amino-2-aminomethylbutyl α ―
chlorocinnamate) (4) HOBACPC (p-hexyloxybenzylidene p'-amino-2-chloro α-propyl cinnamate) (Compounds in this series that have an alkoxy group with the number of carbon atoms from p-hexyloxy to p-dodecyloxy are ferroelectric.) (5) OOBAMBMC (p-octyloxybenzylidene p'-amino-2-methylbutyl α -methyl cinnamate) (6) DOBMBA [p-decyloxybenzylidene
p′-(2-methylbutyloxycarbonyl)aniline] (In this system, compounds having an alkoxy group with the number of carbon atoms of p-heptyloxy to p-tetradecyloxy are ferroelectric.) Ester-type ferroelectric liquid crystal compounds: (1) 4-n-hexyloxyph Enil 4-(2″-
Methylbutyl)biphenyl-4'-carboxylate (2) 4-(2'-methylbutyl)phenyl 4'-octylbiphenyl-4-carboxylate (3) 4-(2'-methylbutyloxy)phenyl
4'-dodecyloxyphenyl-4-carboxylate (Compounds in which the above 2'-methylbutyloxy group is replaced with a 4'-nonyloxy group also exhibit ferroelectricity.) Azoxy-type ferroelectric liquid crystal compounds: (1) PACMB (p-azoxycinnamate methyl 2-butanol) In the composition of the present invention, two or more of the ferroelectric liquid crystal compound and the compound represented by the general formula () may be used as a mixture. In the composition of the present invention, 4 parts represented by the general formula () is added to 100 parts by weight of the ferroelectric liquid crystal compound.
0.01 to 100 parts by weight of -(β-methylbutyloxy)-4'-alkylazoxybenzene is blended.
If the amount is less than 0.01 part by weight, no effect of extending the operating life will be exhibited, and if it exceeds 100 parts by weight, the ferroelectric liquid crystal will be diluted and its properties as a ferroelectric liquid crystal will deteriorate. [Example] Next, the present invention will be explained with reference to Examples. In addition, in the following examples, the phase transition temperature is
Measurement was performed using DSC (Seiko Electronics SSC 580 DS), and confirmation was made by inserting a liquid crystal sealed in a glass plate in a temperature-controlled copper block and observing it with a polarizing microscope. Example 1 [Production of S-(+)-4-(β-methylbutyloxy)4'-heptylazoxybenzene] 32.9 g (0.17 M) of 4-heptylaniline was heated to 0°C.
After cooling, 85 g of a 10% aqueous hydrochloric acid solution was added, and then 12.1 g of sodium nitrite dissolved in 70 ml of water was added. During the dropping, the solution was cooled so that the temperature did not exceed 0°C. After the dropwise addition was completed, the mixture was allowed to react for 30 minutes and then transferred to a dropping funnel.8% containing 16g of phenol was added.
It was added dropwise to 300 ml of NaOH aqueous solution. The temperature was kept below 5°C during the dropping. After the dropwise addition was completed, stirring was continued for 1 hour, and then 10% aqueous hydrochloric acid solution was added until the pH reached 5 to 6 to precipitate the reaction product. The precipitate was separated, washed with water, and then dried under reduced pressure overnight. Petroleum ether 500 after drying
ml and further dried under reduced pressure to give 34.7g.
(0.12M) of 4-hydroxy 4'-heptyl azobenzene was obtained. The yield was 71%. 4-Hydroxy 4'-heptyl azobenzene 10g
(0.034M) with 4.4g of potassium hydroxide
It was dissolved in 1 ml of ethanol and heated under reflux for 6 hours. Next, 10 g of S-(+)-2-methylbutyl bromide was added and the mixture was heated under reflux for 12 hours. After the reaction was completed, the mixture was filtered and the solvent was distilled off. The residue was dissolved in benzene and subjected to column chromatography on silica gel. Benzene was distilled off and dried under reduced pressure to obtain 5.0g (0.014M) of S-
(+)4-(β-methylbutyloxy)4'-heptyl azobenzene was obtained. The yield was 41%.
It exhibited a monotropic cholesteric liquid crystal phase at 33°C to 8°C. S-(+)-4-(β-methylbutyloxy)
4′-heptyl azobenzene 2.0g (0.0055M) 50
ml of glacial acetic acid and stirred while heating to 60-70°C. 1
ml of 30% hydrogen peroxide solution was added and reacted for 1 hour.
Next, 1 ml of 30% hydrogen peroxide solution was added and reacted for 4 hours. Thereafter, 4 ml of 30% hydrogen peroxide solution was added over a period of 8 hours, and the mixture was allowed to react for 6 hours after the dropwise addition was completed. After the reaction was completed, the mixture was extracted with hexane and the solvent was distilled off. It was dissolved in benzene and subjected to column chromatography on silica gel. Distill off benzene and dry under reduced pressure to give 1.8g
(0.0047M) of S-(+)-4-(β-methylbutyloxy)4'-heptylazoxybenzene was obtained. The yield was 85%. The IR, NMR data, and phase transition temperature of this compound are shown below. IR：

[Formula] 1280cm ^-1 Ar-O-CH ₂ 1260cm ^-1 NMR: Ar-C H ₂ - 2.5 (t) 0.7-2.0 methyl, methylene Ar-O-C H ₂ -3.7 (q) Ar 7.7 - 8.2 Phase Transition temperature: Cryst9°C -33°CCh43°C 41°CIso Each abbreviation has the following meaning (the same applies to the following examples). Cryst: Crystal Ch: Cholesteric phase Iso: Isotropic liquid Example 2 [Production of S-(+)-4-(β-methylbutyloxy)4'-hexylazoxybenzene] 30.1 g (0.17 g) of 4-hexylaniline M) at 0℃
After cooling, 85 g of a 10% aqueous hydrochloric acid solution was added, and then 11.6 g of sodium nitrite dissolved in 68 g of water was added. During the dropping, the solution was cooled so that the temperature did not exceed 0°C. After the dropwise addition was completed, the mixture was allowed to react for 30 minutes and then transferred to a dropping funnel.8% containing 16g of phenol was added.
It was added dropwise to 170 g of NaOH aqueous solution. The temperature was kept below 5°C during the dropping. After the addition was completed, stirring was continued for 0.5 hours, and then 10% aqueous hydrochloric acid solution was added until the pH reached 5 to 6 to precipitate the reaction product. The precipitate was separated, washed with water, and then dried under reduced pressure overnight. Petroleum ether after drying
Washed with 500ml and dried under reduced pressure to yield 29.6g.
(0.10M) of 4-hydroxy4'-hexylazobenzene was obtained. The yield was 59%. 4-Hydroxy-4'-hexylazobenzene 8.6g
(0.030M) with 3.3g of potassium hydroxide
It was dissolved in 1 ml of ethanol and heated under reflux for 9 hours. Next, 9.0 g of S-(+)-2-methylbutyl bromide was added and the mixture was heated under reflux for 12 hours. After the reaction was completed, the mixture was filtered and the solvent was distilled off. The residue was dissolved in benzene and subjected to column chromatography on silica gel. Benzene was distilled off and dried under reduced pressure to obtain 5.9g (0.017M) of S-
(+)4-(β-methylbutyloxy)4'-hexylazobenzene was obtained. The yield was 57%.
It exhibited a monotropic cholesteric liquid crystal phase at 11-13°C. S-(+)-4-(β-methylbutyloxy)4'hexylazobenzene 2.5g (7.1
×10 ^-3 M) was dissolved in 50 ml of glacial acetic acid and stirred while heating to 60-70°C. 1 ml of 30% hydrogen peroxide solution was added and reacted for 1 hour. Next, 1 ml of 30% hydrogen peroxide solution was added and reacted for 4 hours. 30% of 4ml in the next 8 hours
Hydrogen peroxide solution was added and the mixture was reacted for 6 hours after the dropwise addition was completed. After the reaction was completed, the mixture was extracted with hexane and the solvent was distilled off. It was dissolved in benzene and subjected to column chromatography on silica gel. Benzene was distilled off and dried under reduced pressure to obtain 1.7 g (4.6×10 ^-3 M) of S-(+)-4-(β
-Methylbutyloxy)4'-hexylazoxybenzene was obtained. The yield was 65%. The IR, NMR data and phase transition temperature of this compound are shown below. IR：

[Formula] 1270cm ^-1 Ar-O-CH ₂ 1245cm ^-1 NMR (Sppm): Ar-C H ₂ -2.6 (t) 0.7-2.0 Methyl, methylene Ar-O-C H ₂ -3.7 Ar 6.7-8.3 Phase Transition temperature: Cryst -2℃ -18℃Ch32℃ 28℃Iso Example 3 [Production of S-(+)-4-(β-methylbutyloxy)4'-octylazoxybenzene] 35g of 4-octylaniline ( 0.17M) was cooled to below 0°C, 85g of a 10% aqueous hydrochloric acid solution was added, and then 12.0g of sodium nitrite dissolved in 68ml of water was added. During the dropping, the solution was cooled so that the temperature did not exceed 0°C. After the dropwise addition was completed, the reaction mixture was allowed to react for 30 minutes, then transferred to a dropping funnel and added with 8% NAOH containing 16g of phenol.
It was added dropwise to 170 g of the aqueous solution. The temperature was kept below 5°C during the dropping. Continue stirring for 1 hour after completion of the dropwise addition, then adjust the pH to 5.
A 10% aqueous hydrochloric acid solution was added until the concentration reached ~6 to precipitate the reaction product. The precipitate was separated, washed with water, and then dried under reduced pressure overnight. After drying, wash with 500ml of petroleum ether and dry under reduced pressure to obtain 30.8g (0.10M) of 4
-Hydroxy-4'-heptyl azobenzene was obtained. The yield was 59%. 4-Hydroxy-
4′-octyl azobenzene 10g (0.032M) at 3.6
The mixture was dissolved in 20 ml of ethanol together with 1 g of potassium hydroxide, and heated under reflux for 6 hours. Next, 9g of S-
Add (+)-2-methylbutyl bromide and add 12
The mixture was heated to reflux for an hour. After the reaction was completed, the mixture was filtered and the solvent was distilled off. The residue was dissolved in benzene and subjected to column chromatography on silica gel. Benzene was distilled off and dried under reduced pressure to obtain 5.7g (0.015M) of S-(+)4-(β
-Methylbryloxy)4'-octyl azobenzene was obtained. The yield was 47%. It exhibited a monotropic cholesteric liquid crystal phase between 6°C and 26°C. S-(+)-4-(β-methylbutyloxy)4'octylazobenzene 2.1g (5.5×10 ^-3 M)
was dissolved in 50 ml of glacial acetic acid and stirred while heating to 60-70°C. 1 ml of 30% hydrogen peroxide solution was added and reacted for 1 hour. Next, 1 ml of 30% hydrogen peroxide solution was added and reacted for 4 hours. Thereafter, 4 ml of 30% hydrogen peroxide solution was added over a period of 8 hours, and after the dropwise addition was completed, the reaction was allowed to proceed for 6 hours. After the reaction was completed, the mixture was extracted with hexane and the solvent was distilled off. It was dissolved in benzene and subjected to column chromatography on silica gel. Distill off benzene and dry under reduced pressure to give 1.7g
(4.3×10 ^-3 M) of S-(+)-4-(β-methylbryloxy)4'-octylazoxybenzene was obtained. The yield was 78%. The IR data and phase transition temperature of this compound are shown below. IR：

[Formula] 1280cm ^-1 Ar―O―CH ₂ 1255cm ^-1 Phase transition temperature: Cryst10℃ -19℃Ch44℃ 42℃Iso Example 4 S―(+)― based on 100 parts by weight of DOBAMBC
A liquid crystal composition was prepared by adding 5 parts by weight of 4-(β-methylbutyloxy)-4-octylazobenzene. Next, a square glass substrate on which a striped ITO film with a pitch of 100 μm and a width of 62.5 μm was provided as an electrode was prepared, and the substrate was placed in an oblique evaporation apparatus with the side on which the ITO film serving as the electrode was placed facing downward. Next, SiO ₂ crystals were set in a molybdenum crucible. After that, inside the vapor deposition equipment
After creating a vacuum state of about 10 ^-5 Torr, SiO ₂ was obliquely vapor-deposited on the glass substrate by a predetermined method to form an obliquely-deposited film of 800 Å (electrode plate A). On the other hand, a polyimide forming solution ("PIQ" manufactured by Hitachi Chemical Co., Ltd.; non-volatile content concentration 14.5 wt%) was applied using a spinner coater onto a glass substrate on which a similar striped ITO film was formed, and the temperature was increased to 120°C. for 30 minutes at 200℃
800℃ for 60 minutes and 30 minutes at 350℃.
A film with a thickness of 1.5 Å was formed (B electrode plate). Next, a thermosetting epoxy adhesive was applied to the periphery of the A electrode plate except for the area that would become the injection hole by screen printing, and then the striped pattern electrodes of the A electrode plate and the B electrode plate were made to intersect at right angles. The two electrode plates were stacked one on top of the other and held with a polyimide spacer so that the distance between the two electrode plates was 2 μ. The liquid crystal composition in an isotropic phase was injected into the cell thus created through the injection port, and the injection port was sealed. The temperature of this cell is lowered by slow cooling.
A pair of polarizers was placed in a crossed nicol state while the temperature was maintained at 65°C, and observation under a microscope confirmed the formation of a monodomain SMC* with a melted helix. Next, a 40V (peak-to-peak), 100Hz square wave was repeatedly applied to this liquid crystal cell at the same temperature. Deterioration was determined by comparing the initial current value and the current value after 500 hours of continuous operation. As a result, while the initial current value was 0.5 μA, the current was 0.7 μA after continuous operation. Example 5 In place of the liquid crystal composition used when preparing the liquid crystal cell of Example 4, 100 parts by weight of DOBAMBC and S
-(+)-4-(β-methylbutyloxy)-
3 parts by weight of 4'-decylazoxybenzene and S
-(+)-4-(β-methylbutyloxy)-
A liquid crystal cell was prepared in exactly the same manner as in Example 4, except that a liquid crystal composition containing 2 parts by weight of 4'-dodecylazoxybenzene was used. In the same manner as in Example 4, deterioration due to continuous operation was investigated from the current value. While the initial current value was 0.6 μA, it was 0.7 μA after continuous operation. Comparative Example 1 Example except that S-(+)-4-(β-methylbutyloxy)-4'-octylazoxybenzene was removed from the liquid crystal composition used when preparing the liquid crystal cell of Example 4. A liquid crystal cell was prepared in exactly the same manner as in Example 4. The current value was measured in exactly the same manner as in Example 4. While the initial current value was 0.6 μA, it was 1.1 μA after continuous operation. Comparative Example 2 In the liquid crystal composition used when preparing the liquid crystal cell of Example 4, S-(+)-4-(β-methylbutyloxy)-4'-octylazoxybenzene was replaced with P-β- A liquid crystal cell was prepared in exactly the same manner as in Example 4 except that methylbutyl-P'-β-methylbutyloxyazoxybenzene was used. The current value was measured in exactly the same manner as in Example 4. While the initial current value was 0.6 μA, it was 1.1 μA after continuous operation. As is clear from the above Examples and Comparative Examples, by adding 4-(β-methylbutyloxy)-4'-alkylazoxybenzene represented by the general formula into the liquid crystal composition, the lifespan of the liquid crystal element can be improved. can be significantly extended. [Effect of the invention] The novel compound 4-(β-methylbutyloxy)4'-alkylazoxybenzene according to the present invention is
It exhibits liquid crystallinity and also has 4-
The liquid crystal composition of the present invention containing (β-methylbutyloxy)4'-alkylazoxybenzene has an extended operating life without impairing the properties of the ferroelectric liquid crystal compound, and the life of the liquid crystal display element. It is suitable for use in liquid crystal display elements, liquid crystal light shutters, etc., and has great industrial significance.

[Brief explanation of drawings]

FIG. 1 is a perspective view schematically showing an optical modulation element using chiral smectic liquid crystal. FIG. 2 is a perspective view schematically showing the bistability of the optical modulation element. DESCRIPTION OF SYMBOLS 1, 1a...Substrate, 2...Liquid crystal molecule layer, 3...Liquid crystal molecules, 4...Dipole moment in the direction orthogonal to the molecules, 5...Upward, 5a...Downward, 6...Voltage application means, 7...First stable state , 7a...second stable state.

Claims (1)

[Claims] 1 General formula (): (In the formula, R represents an alkyl group having 6 to 12 carbon atoms,
* indicates an asymmetric carbon atom) A ferroelectric liquid crystal composition containing at least one compound represented by the following as a compounding component.